Project Requirements

(This text contains extracts from the main sectionof the requirements specification.)

"In order to be successful computer based tutorialmaterial must, from the viewpoint of the student, be simple and interestingto use; and from the viewpoint of the tutor, at a time when pressures uponscarce tutorial time are increasing, it must require no supervision."[SCCC 1992] The key to the software will be finding the balancebetween making the software easy to understand without making the tasksinvolved obvious. The new software will have to, as a minimum, containall the functionality of the previous software. Based upon the learningoutcomes and the description of the previous ACORN BBC software, the followingrequirements can be recognised:

1) Functions - The software will allow the user to usethe key functions. i.e. RTS, CTS, ACK, NACK and Error Check. These willbe available though not in any logical order as that is the purpose ofthe user interaction.

2) Names - The software will differentiate between thetwo stations/users through naming each one with a unique name.

3) Build packet - The software will allow the user toconstruct a packet, incorporating the source and destination addresses,a message and the CRC calculation.

4) CRC - The software will allow the generation of theCyclic Redundancy Check when the packet is being built.

5) Random error generation - The software will randomlyallocate errors in the packets which will be picked up during the errorcheck.

6) Effective error messages - The software will provideclear and concise explanations for errors that occur. However, it willnot provide an solution for rectifying the problem.

7) Effective and easy to use interface - The interfacewill be clear and in an environment that the users can relate to.

Screen Format

"...the quality of the user interface becomes animportant aspect - each package must provide in itself the means to allowits basic use without paper documentation. If a number of packages areavailable for use, they should also all offer a highly similar interface.Thus the student will not spend time learning how to operate each new package- if the interface is clear and consistent there will be no initial discouraginghurdle in the self-motivated use of tutorial software." [HoyleB.S. 1988]

The interface of the software will probably take the formof a windows environment. A vast majority of the software used by the schoolis based in windows and therefore the users (pupils) will already be familiarwith the concepts involved in an environment of this nature. Actions willperformed via a series of selection buttons. A split screen environmentis plausible, displaying both source and destination information. However,it may be more concise to display a main window on the screen along witha smaller ‘status’ window showing the current status of the opposite machine.This will avoid confusion over which is the relevant window. The diagrambelow shows the type of interface that will be used. (NB: This is not aninterface design.)

Throughout process, the ‘status’ window keeps track of statusof opposite PC and ‘memory’ window shows a graphical representation ofany current packets.

The software will also make use of graphics and possibly animation to help describe the processes going on. This is something that was not effectively possible with the old BBC Micro machines and may helpin the users understanding.

Hardware and OS requirements

The hardware and operating system (OS) requirements have been predetermined by the systems available to the school. Therefore, thesoftware will be running on two PC’s, (the specification of the machinesis essentially unimportant. However, they will more than likely containPentium™ processors and have at least 16 Megabytes of memory.) The 2 machineswill be linked by a serial cable connecting the COM ports. The serial cableapproach provides increased flexibility over running the software overthe Ethernet because it ensures that any future upgrade of the school networkwill not leave the software redundant.

The school runs two operating systems: Microsoft Windows3.11™ and Microsoft Windows 95™. Windows 3.11 is still dominant but theschool is considering an upgrade to Windows 95/Windows NT in the near future.Therefore, the software will be written using Windows 95 which will beNT compatible.

 Back to Project Page

Last Updated: 4th February 1998